75. 颜色分类

/**
 * @param {number[]} nums
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var sortColors = function (nums) {
  let l = 0,
    r = nums.length - 1
  for (let i = 0; i <= r; i++) {
    if (nums[i] === 0) {
      swap(nums, i, l)
      // ;[nums[i], nums[l]] = [nums[l], nums[i]]
      l++
    } else if (nums[i] === 2) {
      swap(nums, i, r)
      // ;[nums[r], nums[i]] = [nums[i], nums[r]]
      r--
      i--
    }
  }

  function swap(arr, a, b) {
    let tmp = arr[a]
    arr[a] = arr[b]
    arr[b] = tmp
  }
  return nums
}